1. Field of the Invention
The present invention relates to a light-emitting device that includes a light emitting diode.
2. Description of Related Art
Conventionally, a white light emitting diode that is capable of obtaining white light by covering a blue light emitting diode with a YAG based phosphor that receives blue light and emits yellow light to color mix the blue light from the blue light emitting diode and the yellow light of the YAG based phosphor has been known.
As a white light emitting diode, for example, a lighting system that includes a radiation source such as a blue light-emitting LED, a first fluorescent material that is arranged on the surface of the radiation source, and a second fluorescent material that is piled up on the surface of the first fluorescent material has been disclosed (ref: for example, Japanese Unexamined Patent Publication No. 2009-534863).
In the lighting system, the second fluorescent material made of a red emitting phosphor powder that receives blue light and emits red light is adhered to the surface of the first fluorescent material made of a polycrystalline ceramic of green/yellow emitting garnet that receives blue light and emits green light or yellow light. By mixing the blue light emitted from the blue light-emitting LED, the green light emitted by the first fluorescent material, and the red light emitted by the second fluorescent material, white light that has a color rendering index that is similar to the “sun-like” spectrum is obtained.